University of Hertfordshire

Crystallographic tomography and molecular modelling of structured organic polycrystalline powders

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  • Parmesh Gajjar
  • Thai T. H. Nguyen
  • Jun Sun
  • Ioanna D. Styliari
  • Hrishikesh Bale
  • Samuel A. McDonald
  • Timothy L. Burnett
  • Benjamin Tordoff
  • Erik Lauridsen
  • Robert B. Hammond
  • Darragh Murnane
  • Philip J. Withers
  • Kevin J. Roberts
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Original languageEnglish
Number of pages12
Early online date2 Mar 2021
Publication statusE-pub ahead of print - 2 Mar 2021


A fundamental understanding of the behaviour of polycrystalline materials, including pharmaceuticals, is vital for control of their physicochemical and crystalline properties, which in turn has the potential to improve drug product development for example. In this work, attenuation X-ray computed tomography (CT) and diffraction contrast tomography (DCT) are combined with molecular modelling to understand the powder packing behaviour and crystal interactions of the organic cubic compound hexamine (hexamethylenetetramine). It is the first application of DCT to polycrystalline organic materials. The crystal morphology is predicted through synthonic modelling, with fully 3D-resolved confirmation of the crystallography of the external {110} facets, edges and corner directions by DCT. Analysis of the powder-bed reveals agglomerate structures and orientational texture, with its chemical origins energetically predicted to be face-to-face in accordance with the experimental data. Finally, measurements of crystal & crystallite interactions provide evidence for different mechanisms of powder bed agglomeration.


© The Royal Society of Chemistry 2021. This is an open access article (

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